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A historical summary of observations since 1960 raises questions about the standard solar model (SSM). The SSM ascribes luminosity to hydrogen fusion in the solar core. It assumes the Sun formed suddenly without mass accretion so its interior had the same composition as its surface. The lightest element, hydrogen, accounts for over 90% of the atoms in the Sun's atmosphere. The next lightest element, helium, makes up about 9% of it. All 81 heavier elements together make up less than 0.3 % of the atoms at the solar surface, but almost all those in nearby planets. In contrast to the SSM, measurements since 1960 have revealed evidence of severe mass separation in the Sun and the presence in protoplanetary material of multiple short-lived nuclides and linked chemical and isotopic gradients from nucleosynthesis. By the mid 1970s, measurements suggested that the Sun likely formed on the collapsed core of a supernova and therefore contained few light elements. In the mid-1980s, it was demonstrated that excess light (l) isotopes relative to heavier (h) ones in the solar wind matched nine stages of mass fractionation, each enriching l relative to h by (h/l)1/2. When the photosphere is corrected for this fractionation, the bulk Sun has the composition of meteorites and nearby planets. In the 1990s, isotope ratios were found to be less fractionated in solar flares as if these flares had by-passed 3.4 stages of fractionation. In the year 2000, heavy elements were reported to be enriched by orders-of-magnitude in an impulsive solar flare. Through nuclear systematic it was shown in 2001 that neutron emission from a collapsed supernova core inside the Sun may initiate a chain of reactions that produce luminosity, neutrinos, and the annual solar wind flux of 3 × 1043 H+ per year. These studies offer another explanation for solar luminosity. They do not corroborate the SSM.